In 1970, Pratt was 2-0 with a 5.40 ERA for the Billings Mustangs, walking 18 in 15 innings. His control woes remained in '71 with the Clinton Pilots and Waterloo Royals, with 20 walks in 20 innings; he was 0-1 with a save and a 4.95 ERA and his career was over.